A new ransomware has been discovered by researchers of Proofpoint used in targeting Education & healthcare organisations.
The ransomware used in the campaign was dubbed Defray, based on the command and control (C&C) server hostname used for the first observed attack:
The ransomware is being spread via Microsoft Word document attachments in email.
The researchers observed two targeted attack on Aug. 15, and on Aug. 22, and both appeared to be designed for specific organizations.
The attack on August 15 targeted Manufacturing and Technology verticals, attackers used messages with the subject “Order/Quote” and a Microsoft Word document containing an embedded executable (also an OLE packager shell object).
The attack on August 22, aimed primarily at Healthcare and Education involving messages with a Microsoft Word document containing an embedded executable (specifically, an OLE packager shell object). The attachment features a UK hospital logo in the upper right and purports to be from the Director of Information Management & Technology at the hospital.
If the potential victim double clicks on the embedded executable, the ransomware is dropped with a name such as taskmgr.exe or explorer.exe in the %TMP% folder and executed.
The ransomware contains a hardcoded list of file extensions, shown below, for files that it will encrypt (although we observed others such as .lnk and .exe encrypted that were not on this list). The file extensions of modified files were not changed. We observed that the modified files all end in bytes “30 82 04 A4 02 01 00 02 82 01 01 00 9F CF 52 84” for our sample.
Defray has been observed communicating with an external C&C server via both HTTP (clear-text, shown in Figure 4) and HTTPS, to which it will report infection information.
After encryption is complete, Defray may cause other general havoc on the system by disabling startup recovery and deleting volume shadow copies. On Windows 7 the ransomware monitors and kills running programs with a GUI, such as the task manager and browsers.
“Defray Ransomware is somewhat unusual in its use in small, targeted attacks. Although we are beginning to see a trend of more frequent targeting in ransomware attacks, it still remains less common than large-scale “spray and pray” campaigns. It is also likely that Defray is not for sale, either as a service or as a licensed application like many ransomware strains. Instead, it appears that Defray may be for the personal use of specific threat actors, making its continued distribution in small, targeted attacks more likely” concluded Proofpoint.